1. Field of the Invention
The present invention relates to devices used to aid in and provide ventilation and more particularly to respiratory masks having intraoral mouthpieces to provide improved sealing to a wearer.
2. Description of Related Art
Respiratory masks are commonly used in emergency care and critical care situations. They may be used in conjunction with bag valves to deliver gases under positive pressure to a patient not capable of adequately breathing independently. Respiratory masks, in conjunction with a one-way valve, are also used by rescuers to provide mouth-to-mask resuscitation to a person who is not breathing. Additionally, respiratory masks are used in conjunction with bilevel positive airway pressure and continuous positive airway pressure machines to aid respiration in certain instances.
The traditional respiratory mask includes a fixed domed or cup-shaped device that fits over the mouth and nose of a wearer. The edge of this dome or cup fits against the face of the wearer. Air or another gas or mixture of gases is introduced into the traditional mask through an opening that is typically at the peak of the dome or cup. The integrity of the seal between the edge of the traditional respiratory mask and the face of the wearer is critical to the gas delivery effectiveness of a traditional respiratory mask. While commonly used in the healthcare industry, these masks have several serious shortcomings.
Healthcare providers must have access to several sizes of traditional respiratory masks for use on people of different ages and facial sizes. This need for access to several different sized masks is particularly burdensome to emergency medical technicians who must transport medical supplies in a limited amount of space. Therefore, to ease this burden on emergency medical personnel, an improved respiratory mask would be wearable by a large portion of the population regardless of age or face size.
Perhaps the largest shortcoming of the traditional sized respiratory masks is that despite the availability of several sizes of mask, the wide variations in facial features among people prevent these masks from sealing effectively. Where the person to be ventilated has facial hair, traditional respiratory masks are almost completely incapable of forming a seal with the person's face. This deficient sealing causes leakage around the edges of the mask and significantly decreased gas delivery efficiency. The traditional respiratory masks frequently leak near the nasal bridge section of the mask, leading to drying of the cornea and ultimately keratitis.
An inherent problem with traditional respiratory masks that contributes to gas leakage is that the gas must pass from the mask through the lips and teeth of the person being ventilated before being received in the person's mouth, or it must pass through the nose of the person being ventilated. The lips and teeth are resistance points that disrupt the laminar flow of the gas, leaving the incomplete seal around the edge of the mask as a path of least resistance from which the gas leaks. Likewise the nasal passages are narrow, with turbinates to disrupt flow in addition to inherent mucous and debris accumulation, thereby providing a restrictive, nonlaminar flow circuit.
Where a bag valve is used, it optimally requires two healthcare providers to effectively ventilate a person. It requires both hands of one of the healthcare providers to hold the respiratory mask and apply pressure onto the face of the person to be ventilated in an attempt to seal the mask, while another healthcare provider squeezes the bag. Such an arrangement is highly disadvantageous for long term ventilation of a person, such as occurs when a patient is transported or under anesthesia in an operating room. Healthcare providers using these traditional respiratory masks will often attempt to compensate for the deficient seal by either applying excess pressure to the mask onto the face of the person being ventilated or, in the case of a bag valve, by squeezing the bag with maximal intensity. The application of excessive pressure by the healthcare provider on a traditional respiratory mask is problematic for several reasons. The pressure required to be applied for proper sealing of the face mask can quickly lead to healthcare provider fatigue. A fatigued healthcare provider may be less able to apply sufficient pressure onto the traditional respiratory mask to reduce its inherent leakage and may have difficulty performing this and other critical tasks. Additionally, the application of excessive pressure to a traditional respiratory mask onto the face of the person being ventilated will cause the mask to develop pressure points on the bridge of the nose, cheek bones, and chin. This pressure could lead to irritation of wearer's face and discomfort or pain to the wearer.
Proper head and neck position. i.e. neck extension, and maneuvers such as the chin-lift and jaw-thrust are also required for efficient ventilation by opening and maximizing the patency of the airway. These tasks, in addition to the above task of preventing leaks can overwhelm the healthcare provider and often require two providers to ventilate a patient adequately.
Squeezing the bag with maximal intensity in an attempt to compensate for deficient sealing of a traditional respiratory mask is likewise problematic. The increased inspiratory forces may exceed the opening pressure of the esophagus, possibly leading to esophageal and gastric dilatation and subsequent aspiration.
Clearly, there is a need for an improved respiratory mask addressing the shortcomings of the traditional respiratory mask. Others have attempted to address the problems with traditional respiratory masks. Their attempted solutions, however, have fallen far short of addressing all of the problems of the traditional respiratory mask and have created new problems.
Several attempts at improving the traditional respiratory mask have done so through the use of a gas delivery tube feeding into an intraoral mouthpiece with a bite block. An intraoral mouthpiece eliminates one shortcoming of traditional respiratory masks: the reliance on a nearly impossible to achieve seal between the mask and the outside of the mask wearer's face. Intraoral mouthpieces also bypass the mask wearer's lips, which posed a source of resistance to flow and disruption of laminar flow to traditional respiratory masks. Nevertheless, despite these advantages over the traditional respiratory masks, the integration of a bite block into the design creates several disadvantages.
Mouthpieces having bite blocks or bite plates cannot be safely inserted into the mouth of someone who is combative, semiconscious, or having a seizure. A healthcare provider attempting to insert a mouthpiece with a bite plate by prying open the jaws of a person to be ventilated would do so at risk of sustaining bite related injuries, possibly as severe as amputation of a digit or contracting an infectious disease. Forced insertion of a mouthpiece with bite block into the mouth of a person to be ventilated also risks the person's aspiration of blood, teeth, dental fragments, or fragments of the bite block broken off during insertion. Another disadvantage of mouthpieces with bite blocks is that their wearers will reflexively bite down and typically they may not be worn by persons with missing teeth, dentures, or those with facial injuries, jaw trauma or fractures. Further, because people wearing mouthpieces with bite blocks will bite down on the blocks, the use of these mouthpieces can quickly lead to jaw fatigue and discomfort. These bite blocks may also stimulate a gag reflex and increase the aspiration risks in the awake or semiconscious patient.
The integration of a mouthpiece having a bite block with an intraoral oropharyngeal airway presents additional disadvantages. Intraoral oropharyngeal airways are used to prevent the tongue of the person to be ventilated from blocking the airway while providing a direct path for gas delivery to the pharynx. Intraoral oropharyngeal airways are typically inserted either by rotating the oropharyngeal airway 180° as it is inserted or by using a tongue blade. If the oropharyngeal airway is to be integrated with the mouthpiece, it would be impossible for the airway to be inserted with a 180° rotation method as the bite block would collide with the teeth of the person to be ventilated. A tongue blade, which would need to be carried by an emergency healthcare provider such as an emergency medical technician, would be necessary to insert the intraoral oropharyngeal airway. Therefore, the integration of a mouthpiece with a bite block is also undesirable.
Additionally, while intraoral mouthpieces with incorporated bite blocks address the problem of gas delivery to the mouth of a person, they can create gas leakage through the nose of the person to be ventilated. The prior art respiratory devices having intraoral mouthpieces with bite blocks deliver gas to the mouth of a person to be ventilated without providing for sealing the nose of the person to be ventilated. Standard nose occluding clips could be used to close the nostrils of a person being ventilated with an intraoral mouthpiece with bite block, but this solution would require a healthcare provider to have access to nose occluding clips. During ventilation with an intraoral mouthpiece, large volumes of otherwise delivered gas will escape through the nose of the person being ventilated. Therefore, it is desirable for an intraoral respiratory mask to include an integrated nose clamp.
While the respiratory mouthpieces with bite blocks do address several problems of the traditional respiratory mask, the bite blocks make these devices impossible to use on certain individuals (with dentures, missing teeth, or facial/jaw trauma), dangerous to use on others (combative or semiconscious), and uncomfortable to use on everyone. Moreover, since prior art intraoral mouthpieces with bite blocks do not address gas leakage from the nose of the person to be ventilated, they are still inefficient gas delivery devices. Lastly, none of the mouthpieces with bite blocks can accommodate typical oropharyngeal airways.
There have been attempts to address the problems of the traditional respiratory masks without using a bite block or bite plate. But, these attempts also create problems. For example, there are also prior art intraoral mouthpieces featuring a conduit that is flanged on one end. The flanged end is to be placed between the lips and gums of the person to be ventilated. A healthcare provider would ventilate the person with the flanged conduit device by exhaling through the conduit. The flanged mouthpiece, while likely an improvement over the traditional respiratory mask, has serious wear and comfort issues. The intraoral flanged portion of the device extends just above and below the gum-line in the person to be ventilated. Also, the flanged end does not extend posteriorly or laterally in the mouth of the person to be ventilated beyond the front teeth. Therefore, while the flanged end of the device provides a seal between the material of the flanged end and the inside of the lips and gums of the person to be ventilated, that seal still leaves avenues for gas leakage. With the flanged conduit respiratory device, air may leak around the flanged end at the top and bottom (between the flanged end and the gums above and below the gumline of the person to be ventilated) and the sides (towards the canine teeth and molars of the person to be ventilated).
A further shortcoming of the flanged conduit respiratory device is that the flanged end of the conduit does not lie flush to the teeth and gums of the person to be ventilated. Rather, the flanged end has an arcuate profile designed to mate with the inside of the lips of the person to be ventilated. Thus, only the material nearest the edge of the flanged end actually forms a seal with the mouth of the person to be ventilated. This limited sealing area will result in a pressure concentration, irritation, and discomfort on the gums of the person to be ventilated, possibly leading to lacerations and bleeding. Therefore, while the flanged conduit respiratory device is an attempt to address the problems of the traditional respiratory mask, it suffers the disadvantages of inadequate intraoral sealing due to a small seal surface area and gum irritation or injury to the wearer. Further, there is no nasal occlusive component and the device is incompatible with an oropharyngeal airway.
Another prior art approach to address the problems of the traditional respiratory mask uses an inflatable intraoral seal bladder attached to an intraoral mouthpiece and a conduit. Though the inflatable seal rests in the space between the gum and the inner lips of the wearer, air/gas can still escape around it when no external pressure is applied to the face and lips of the wearer. In addition, the inflatable seal may cause pressure points and irritate the gum and mucosa of the wearer. The inflatable seal approach is also undesirably complex, requiring inflation of both an intraoral seal and a separate nasal block before use, and this complexity necessitates several component elements that are in danger of being bitten off and rendered ineffective by a combative or semi-conscious person. Time, which is very limited in a critical or emergent resuscitation, is also required to inflate both the intraoral seal and the nasal block. This device is also incompatible with current oropharyngeal airways.
As is evidenced by the above discussion of the related art, there is a need for an improved respiratory mask with improved sealing and gas delivery capability that can be safely inserted in mouths of combative and semiconscious persons and that is comfortable for people to wear. The improved respiratory mask should also allow a single healthcare provider to ventilate a person without significant gas leakage. It must also allow for the use of an oropharyngeal airway, when one is needed, to ensure a patient airway.